The chairman of Barclays apologised to shareholders today as he moved to head off a showdown over the pay of chief executive Bob Diamond.

At the start of the bank's annual meeting, Marcus Agius admitted the bank's bosses "have not done a good enough job in articulating our case".

Diamond received £17.7m in salary, bonus, benefits and vested long-term share awards last year - despite admitting his bank's performance was "unacceptable".

The meeting was due to hear calls for remuneration committee chairman Alison Carnwath to stand down and for the 2011 pay report to be thrown out.

Agius, who also faces a significant vote against his re-election, said: "I assure you that in the future we will be engaging differently and more purposefully with shareholders in order to ensure that we obtain a broader level of support on remuneration policy and practice."

Outside the meeting at Royal Festival Hall, the bank's bosses had to contend with dozens of protesters from the World Development Movement and Robin Hood Tax campaign.

The Robin Hood campaigners posed with a giant cheque to represent the implied subsidy provided to banks by the taxpayer.

Diarmaid McDonald, 31, with the Robin Hood movement, said: "We should not be held to ransom by the financial sector. They are as much part of this society as we are."